Self-destructing fuze system for rotating projectiles



R. M. HAIKEN 3,353,486

SELF-DESTRUCTING FUZE SYSTEM FOR ROTATING PROJECTILES Nov. 21, 1967Filed March 5, 1966 lllllh United States Patent the Army Filed Mar. 3,1966, Ser. No. 533,377 3 Claims. (Cl. Mil-70.2)

ABSTRACT 0F THE DISCLOSURE An auxiliary fuze system for destroying anexplosive projectile after a time delay. An unbalanced rotor element ismounted coaxially with the projectile on the spin axis to drive amechanical timing gear train or to provide a magnetic field to generatea current in generator windings associated therewith in response torotation of the projectile in flight. An auxiliary fuze train forexploding the main charge of the projectile is initiated by current fromthe generator windings through switch means provided by a seriescapacitor in circuit therewith. The capacitor is arranged to break downafter a delay time during which it charges to the break-down point, orto charge over a similar delay time and fire a bypass transistor switchmeans for applying the generator current to fire the auxiliary fuzetrain. The gear train operates to effect a delayed mechanical switchclosing for the same purpose. Any firing-current or power source may beused in this case.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes without the payment to me ofany royalty thereon.

The present invention relates to rotating fuzed projectiles of the typethat detonate on impact with a target such as an enemy aircraft, andmore particularly to a system for detonating the charge of theprojectile if the main fuze fails to impact upon a target.

Frequently, when firing against enemy aircraft flying over friendlyterritory, the projectile may fail to impact its target. If allowed tocontinue its flight, the projectile may impact and damage groundinstallations or personnel, or become a hazard if it falls and fails todetonate. The system of the present invention of the self-destructingtype will detonate such a projectile after it has passed its target andbefore it impacts the ground.

This need for self-destructing fuze means has existed for as long ashigh explosive projectiles have been used as a defense against aircraft.The problem has been solved in the past by various mechanical timedevices, mechanical spin sensors, or pyrotechnic time self-destructingdevices.

It is an object of this invention, therefore, to provide an improvedself-destructing system for projectiles having means whereby, if themain fuze fails to detonate, an auxiliary fuze will do so and destroythe projectile after it has passed its objective. Over friendlyterritory thus if the projectile misses its target, the auxiliary fuzeexplodes the projectile before it can fall on anyone therein.

It is a further object of this invention to provide an improvedself-destructing fuze system for rotating fuzed projectiles whichincludes a series of operative elements adapted for electrical ormechanical operation with substantially equal effectiveness.

It is also a further object of this invention to provide an improvedself-destructing fuze system for rotating projectiles which isresponsive to rotation of the projectile in operation and includes aninertial power unit operating on the spin axis of the projectile toproduce the timing operation and auxiliary fuzing of the projectile.

3,353,486 Patented Nov. 21, 1967 In accordance with the invention, abasic component is an unbalanced rotor whose axis of rotation is locatedon the center line of the projectile, which is also the axis of spin,but Whose center of mass is remote from the axis of rotation. Theunbalanced rotor is then utilized to provide energy storage, eitherelectrical or mechanical, and further conversion to chemical action ordetonation, to fire the main charge independently of any fuze train andfiring means provided for the projectile on impact. Because of theseparation of the center of mass and the axis of spin, the rotor elementtends to remain stationary relative to the earth and the projectilespins in its ballistic flight about the stationary rotor element. Thus,the rotor relies upon inertia and gravity forces for its operation. Therotor corresponds to the power unit and is connected to suitableintegrator and convertor means which initiates the destruction of theprojectile through a fuze train, if required, and the projectile maincharge. The critical total power output is dependent upon projectilespin rate and distance or time of flght to the desired destructionpoint, and is affected by the inherent drag in the power unit.

The invention will further be understood from the following description,when considered with reference to the accompanying drawing, and itsscope is pointed out in the appended claims.

In the drawing,

FIG. 1 is a schematic block diagram of a self-destructing fuze systemfor a rotating projectile showing the main elements thereof and theiroperative relation in accordance with the invention,

FIG. 2 is a side view in elevation of a typical power unit of theelectrical type for the system of FIG. 1, partly in section and partlybroken away, to show the interior elements thereof, together withcircuit connections therefor, in accordance with the invention,

FIG. 2A is a schematic circuit diagram of a modification of a portion ofthe circuit of FIG. 2 in accordance with the invention,

FIG. 3 is a cross-sectional view of the entire unit of FIG. 2 taken onthe section line 3-3 to show further details thereof in accordance withthe invention, and

FIG. 4 is a schematic diagram of the system of FIG. 1 adapted formechanical operation and showing a typical arrangement for the entireunit integrating means and conversion means of the system of FIG. 1, inaccordance with the invention.

Referrin to the drawing, wherein like elements are designated by likereference characters throughout, and referring particularly to FIG. 1, arotating projectile, indicated in dash and dot lines at 5, includes inthe present example, a piezoelectric generator or transducer 6 at theforward end for generating a voltage upon impact. This element is oftenreferred to as a lucky. This generated .voltage is applied to fire afuze train 7 as indicated by the arrowed line 8, and this in turn firesthe main charge 10 of the projectile as indicated by the arrowed line 9.

The main fuze system of the projectile in the present example thusincludes the piezoelectric generator or lucky 6, the fuze train 7 andthe connecting lines 8 and 9 for the main charge 10. In accordance withthe invention, an auxiliary fuze system is also connected with the maincharge to effect independent firing thereof should the projectile failto impact a target within the desired range.

The auxiliary fuze system, placed to the rear of the main charge in thepresent example, includes energy sup ply means such as the power unit 12which operates upon rotation of the projectile, integrator means 14which operates to accumulate the energy output of the power unit 12through connection therewith as indicated at 13, energy conversion meanssuch as a converting unit or element 16 which converts the accumulatedenergy from the inte grator 14, through connection therewith asindicated at 15, for firing the fuze train 18 through an outputconnection 17 and this in turn fires the main charge through theconnection 19.

In operation the integrator means 14 accumulates the energy output ofthe power unit 12 and when a given total output has been achieved, asover a given number of revolutions of the projectile, it accumulates asufficient quantity of energy to trigger the converter means 16 and sofire the charge through the fuze train. This is after the lucky or mainfiring element 6 and its main fuze train 7 have failed to operate byreason of missing the target. The critical total power output isdependent upon the projectile spin rate and the time of flight throughthe distance to the desired destruction point which is beyond theestimated distance from the target. This disance to the destructionpoint is thus measured in number of revolutions of the projectile whichcan be determined. The energy accumulated by the integrator for applyingto the converter is designed to be a maximum to insure operation at apoint beyond the proper firing point for the projectile.

This system as shown in FIG. 1 is adapted to operate either by theprinciple of operation outlined, through electrical connection means, orthrough mechanical means as may be desired or best suited to therequirements of a given projectile or application. If it is desired toutilize the principle of operation, as described, in an electricalconfiguration, the power unit 12 is a generator which operates toproduce output current or energy upon rotation of the projectile inflight after firing. One arrangement of such a generator in accordancewith the invention utilizing the unbalanced rotor as above referred to,is shown in FIGS. 2 and 3 to which attention is now directed along withFIG. 1.

The power unit or generator 12 of the present example is provided withan outer elongated cylindrical casing 22, preferably of plastic or lightinsulating material, on which are placed a number oflongitudinally-extending generating windings, such as two in the presentexample, as shown at 23 and 24. These are connected in series aidingrelation to each other and have respective terminal ends or leads 25 and26. The lead 25 is connected directly with the integrator 14 asindicated at 13 while the lead 26 is connected therewith, as indicatedat 13, through a control switch 28 and a connecting lead 29.

The windings 23 and 24 are excited in operation by a rotor 30 of anelongated flat bar type having north and south poles 31 and 32 alongopposite edges as indicated in FIGS. 2 and 3. The rotor is provided witha longitudinally-extending shaft 33 which is off-center with respect tothe body of the rotor and extends along one edge thereof, presently nearthe north pole of the magnet. The shaft 33 is mounted in suitable endhearings in the casing 22, one of which is indicated at 34. The axis ofthis shaft extends along the spin axis of the projectile and the centerof the casing 22, or in other words the unbalanced weight or rotor 30has its axis of rotation located on the center line of the projectilewhich is also the axis of spin, while its center of mass, indicated at35 in FIG. 3, is remote from the axis of rotation.

Because of the separation of the center of mass and the axis of spin,the rotor element 30 tends to remain stationary relative to the earthwhile the projectile 5 and the remainder of the elements about it spinsin ballistic flight. This causes the rotor pole to be passed by therotating coils 23 and 24 to effect a generation of voltage therein and,since they are connected in series aiding relation, the voltage outputof both coils is added and derived at the terminals 25 and 26. Presentlythe switch 28 is of the inertia type which closes only when a very highacceleration is attained, as when the projectile is launched into itsinitial flight.

An electrical storage capacitor 37 in the integrator 14 is connectedwith the leads 25 and 29 through the terminals 13, as indicated, andthence through a series connection with the converter 16 at theterminals or connection elements 15 and through an internal fuze element39 therein of the series resistance type. The latter is associated withan electrical detonator 40 which, in turn, is connected through the fuzetrain 18, at its input and output connections 17 and 19, with the maincharge 10 to which is also connected the main fuze train connection 9 asdescribed hereinbefore.

The capacitor 37 of the integrator means 14 is adapted to store anexcessive charge suflicient to close a normallyopen transistorizedby-pass element 38 connected in parallel relation thereto. Current fromthe generator is then applied directly through the by-pass 38 to theelectrical fuze element 39 which, in turn, then ignites or fires theelectrical detonator 40. When this detonates the ignition is then passedon through the fuZe train 18 to the main charge 10 and fires the latter,thereby destroying the projectile shortly after it passes its objective,as provided by the rotation of the projectile to that point.

In FIG. 2A a capacitor 37A is provided in series with the fuze element39 as a modification of the circuit. This is a low-capacity capacitorwhich breaks down and discharges when the appropriate charge level isreached. Thus in itself it provides a switch for closing the circuitwith the fuze element 39 and provides a direct connection therewith tothe generator windings 23 and 24. This effects the same discharge of thedetonator 40 and the main charge it as in the previous example. Bothcircuits utitize the electric detonator means 39-40 as the converter. Inone circuit, the generator output from the windings 23 and 24 chargesthe capacitor 37 of higher capacity than the critical charge so thatwhen the critical charge is attained, the transistorized element 38 ofthe circuit shorts the capacitor 37. The energy stored in the capacitorinitiates the electrical detonator 39-40 which transmits the detonationto other elements of the fuze train 18 and on to the main charge it). Inthe modified circuit of FIG. 2A, the capacitor 37A is of such lowcapacity that it breaks down when the critical charge is attained. andcauses initiation of the electric detonator 39-40 as before.

If it is desired to utilize the principle of operation described, in amechanical configuration, the system of FIG. 4 may be used, which is nowreferred to along with the preceding figures. in this mechanicalconfiguration the power unit 12A is substantially the same as theelectrical power unit of FIG. 2 without the windings and Withoutmagnetizing the rotor 30A. The rotor 30A operates as an unbalancedweight whose axis of rotation is located on the center line of theprojectile as before and this axis is also the axis of spin while thecenter of mass of the rotor is remote from its axis of rotation. Therotor element 30A thus tends to stand still in flight while theremainder of the projectile rotates about it.

In this case the shaft 33 is connected to a mechanical integrator means14A which is a gear train 45 having an input gear 46 on the power-unitshaft 33 and about which the gear train rotates to drive an output shaft47 in connection with a converter 16A which is an indexed detonatorhaving an operating disk or rotating element 48 and a trip mechanism 4-9associated therewith for triggering the detonator 40A after theconverter has rotated a certain number of times in flight to bring theoperating elements of the two devices 48 and 49 together at apredetermined time in the flight which is after the time when theprojectile should have reached its target.

Thus in the present example, the shaft 33 of the powerunit is fixed tothe input gear 46 and drives the integrator 14A which is the gear trainof suitable design. The gear train drives the converter 16A whichincludes a timing mechanism that, at the proper time, utilizes themechanical output of the gear train to initiate the detonating device40A and hence set off the fuze train 18, as before,. for the main charge1Q,

The operating sequence for the self-destructing fuze system in theelectrical configuration shown in FIGS. 2 and 3 may briefly be describedto further indicate the manner of operation of the system. Knowing therange or time of the flight at which it is desired to destroy theprojectile and the total number of revolutions the projectile may haveattained when it reaches that point, the fuze components are designed tomatch for this timing. Upon the launch of the projectile 5 a set-backmechanism, hereinbefore referred to and indicated at 50 in FIG. 2retracts, thereby leaving the magnetized rotor 30 free to tend to remainstationary in rotation with respect to the earth while the windings 23and 24 spin around it, thus generating electrical energy which is afixed output for each revolution of the projectile. At the time theset-back device 50 operates, the inertia switch 28 closes thus allowingthe remainder of the circuit to energize. The output of the generator orpower unit 12 charges the capacitor 37 and when the charge reaches therequired level, the capacitor 37 is dischargd as the switch is closedand the electric detonator 3940 is initiated. The detonator theninitiates the remainder of the fuze train 18 which, in turn, initiatesthe main charge and destroys the projectile.

Thus in accordance with the invention a rotating fuzed projectile isprovided with an auxiliary fuze device or system so that if the mainfuze fails to detonate by reason of impact, the relative rotationbetween an unbalanced armature element and other electrical ormechanical elements of the auxiliary fuze carried by the projectilecauses suiiicient energy to be generated to detonate the auxiliary fuze.Thus if the projectile misses its target, the auxiliary fuze system willexplode the projectile before it can fall on friendly territory.

I claim:

1. In a rotating fuzed projectile having a main detonating charge and amain fuze train operative to fire said charge on impact, an auxiliaryself-destructing fuze system therefor comprising, means providing asupply of energy operative upon rotation of said projectile in flight,integrator means connected to said energy supply means for accumulatingthe energy output therefrom over a predetermined time of flight asmeasured by the number of revolutions of said projectile, convertermeans connected with said integrator means for operation in response toenergy storage by said integrator means reaching a predetermined level,a second fuze train connected with said converter means and responsiveto operation thereof providing a detonation-propagating connectionbetween said convertor and said main charge for eifecting detonationthereof independently of said main fuze train of said projectile, saidenergy supply means including an unbalanced rotor element the axis ofrotation of which is adapted to be located on the center line of theprojectile which is the axis of spin thereof and whose center of mass isremote from the axis of rotation, and the integrator and converter meansbeing connected in series relation in the order named with said energysupply means and responsive to rotation of the projectile about saidunbalanced rotor to apply a regulated and converted energy outputtherefrom to said main charge as an auxiliary fuze line.

2. A self-destructing fuze system for a rotating fuzed projectile havinga main detonating charge and a main fuze train therefor normallyoperated from impact, comprising in combination, an unbalanced rotorelement having an axis of rotation adapted to lie along the center lineof the projectile and on the spin axis thereof and having a center ofmass remote from said axis of rotation, means for deriving and storingoutput energy from the rotational spin of said projectile about saidaxis of rotation of the rotor element, means connected with said rotorelement for storing said energy output over a predetermined rotationallimit representative of a desired distance of travel of said projectile,a second fuze train for said main charge, and means for converting andapplying said stored energy to effect detonation of said main chargethrough said second fuze train independently of the main fuze of saidprojectile, said rotor element being magnetized and provided withelectric generator windings associated therewith to generate electriccurrent upon rotation of said projectile, and the storage meansincluding a capacitor and a detonator element connected serially incircuit with said generator windings for receiving its charge therefrom,and said capacitor being subject to by-pass in response to energystorage thereby to a predetermined level.

3. A self-destructing fuze system for rotating projectiles and the likehaving a main detonating charge and a fuze train operative to fire saidcharge on impact, comprising in combination, a power unit operative onrotation with and on the axis of a projectile to generate acharge-firing current, a storage capacitor and an electric detonator forsaid main charge connected serially in circuit with said power unit, atransistor connected with said capacitor to fire in response to apredetermined charge carried by said capacitor and effect currentdischarge from said power unit through said detonator for firing themain charge, said power unit including a magnetic rotor element andgenerator output windings rotatable with the projectile about said rotorelement, and said rotor element being mounted with its axis of rotationon the spin axis of the projectile but with its center of mass offsetfrom said spin axis in operation.

References Cited UNITED STATES PATENTS 1,755,023 4/1930 Ruehlemann10270.2 2,825,283 4/1958 Sobelman 10270.2 2,856,820 10/1958 Schmued etal. 102-79 X 2,891,479 6/1959 Alexander et al. 102-70.2 2,978,983 4/1961 Okstein et al. 102-79 2,981,890 4/ 1961 Ruehlemann 102--70.2 X2,991,716 7/1961 Israel et al. 102--70.2 3,008,416 11/1961 Ruehlemann102-70.2 3,088,409 5/ 1963 Yavelberg 102-70.2 3,241,373 3/1966 Rickettset al.

BENJAMIN A. BORCHELT, Primary Examiner.

W. C. ROCH, T. H. WEBB, Assistant Examiner.

1. IN A ROTATING FUZED PROJECTILE HAVING A MAIN DETONATING CHARGE AND AMAIN FUZE TRAIN OPERATIVE TO FIRE SAID CHARGE ON IMPACT, AN AUXILIARYSELF-DESTRUCTING FUZE SYSTEM THEREFOR COMPRISING, MEANS PROVIDING ASUPPLY OF ENERGY OPERATIVE UPON ROTATION OF SAID PROJECTILE IN FLIGHT,INTEGRATOR MEANS CONNECTED TO SAID ENERGY SUPPLY MEANS FOR ACCUMULATINGTHE ENERGY OUTPUT THEREFROM OVER A PREDETERMINED TIME OF FLIGHT ASMEASURED BY THE NUMBER OF REVOLUTIONS OF SAID PROJECTILE, CONVERTERMEANS CONNECTED WITH SAID INTEGRATOR MEANS FOR OPERATION IN RESPONSE TOENERGY STORAGE BY SAID INTEGRATOR MEANS REACHING A PREDETERMINED LEVEL,A SECOND FUZE TRAIN CONNECTED WITH SAID CONVERTER MEANS AND RESPONSIVETO OPERATION THEREOF PROVIDING A DETONATION-PROPAGATING CONNECTIONBETWEEN SAID CONVERTOR AND SAID MAIN CHARGE FOR EFFECTING DETONATIONTHEREOF INDEPENDENTLY OF SAID MAIN FUZE TRAIN OF SAID PROJECTILE, SAIDENERGY SUPPLY MEANS INCLUDING AN UNBALANCED ROTOR ELEMENT THE AXIS OFROTATION OF WHICH IS ADAPTED TO BE LOCATED ON THE CENTER LINE OF THEPROJECTILE WHICH IS THE AXIS OF SPIN THEREOF AND WHOSE CENTER FO MASS ISREMOTE FROM THE AXIS OF ROTATION, AND THE INTEGRATOR AND CONVERTER MEANSBEING CONNECTED IN SERIES RELATION IN THE ORDER NAMED WITH SAID ENERGYSUPPLY MEANS AND RESPONSIVE TO ROTATION OF THE PROJECTILE ABOUT SAIDUNBALANCED ROTOR TO APPLY A REGULATED AND CONVERTED ENERGY OUTPUTTHEREFROM TO SAID MAIN CHARGE AS AN AUXILIARY FUZE LINE.